Download Alpha 9500 HF Specifications

Alpha Radio Products
Product Release 1
Alpha 9500 HF Linear Amplifier
Operating Manual
Alpha Radio Products
www.alpharadioproducts.com
Product Release 1
Document Issue 1, Revision 7
June 2009
DOCNUMBER 9500
Document Issue 1, Revision 7
June 2009
i
Alpha 9500 HF Linear Amplifier Operating Manual
Alpha Radio Products
Product Release 1
Alpha 9500 HF Linear Amplifier Operating
Manual
Prepared for Alpha Radio Products by: MRH/LJW
Technical contact: [email protected]
To obtain copies of this document, go to www.alpharadioproducts.com
Copyright © 2007–2009 Alpha Radio Products, Inc. All rights reserved.
Specifications subject to change without notice.
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Contents
Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1 Product Description 1-1
1.2 Product Capabilities 1-2
1.3 Safety Considerations 1-2
1.4 Related Products 1-3
1.5 Assistance 1-4
2. Amplifier Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.1 Cathode (Input-Match) Board 2-2
2.2 Center-Partition Board 2-3
2.3 Connections 2-3
2.4 Controls and Display 2-3
2.5 Display Board 2-5
2.6 Firmware 2-5
2.7 Master-Control Board 2-6
2.8 Output-Tank Circuit 2-6
2.9 Power Supply 2-7
2.10 Tube and Tube Deck 2-8
3. Installation Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1 Prepare Your Station 3-1
3.2 Unpack the Amplifier and Transformer 3-2
3.3 Install the Transformer 3-2
3.4 Connect the Transformer 3-2
3.5 Connect the Cables 3-3
3.6 Set the Input Drive 3-3
3.7 Connect the Transceiver 3-3
4. Preparing Your Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1 Prepare Your Station 4-1
4.2 Limitations of Operation at 90–130 VAC 4-4
5. Setting Up the Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1 Unpack the Amplifier and Transformer 5-1
5.2 Install the Transformer 5-3
5.3 Connect the Transformer 5-4
5.4 Connect the Cables 5-7
5.5 Set the Input Drive 5-10
5.6 Connect the Transceiver 5-10
6. Operating the Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.1 Operate the Amplifier 6-1
6.2 (Optional) Set Up to Operate from a PC 6-3
6.3 Put the Amplifier into the Desired State 6-3
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6.4 Tune the Amplifier 6-5
6.5 Program the Amplifier Memory 6-9
7. Operating the Amplifier from a PC Interface
7.1 Set Up to Operate from a PC 7-2
7.2 Operate from the PC 7-2
. . . . . . . . . . . . . . . . . . 7-1
8. Maintaining and Upgrading the Amplifier . . . . . . . . . . . . . . . . . . . . 8-1
8.1 Clean the Chassis 8-1
8.2 Retune the Amplifier 8-2
8.3 Replace the Tube and Fuses 8-3
8.4 Upgrade Firmware 8-4
9. Diagnosing Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
9.1 Overview 9-1
9.2 Fault Codes and Resolutions 9-1
Terminology 1-1
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List of Procedures
List of Procedures
Procedure 4-1, “Prepare your station,” page 4–1
Procedure 5-1, “Unpack the amplifier and transformer,” page 5–1
Procedure 5-2, “Install the transformer,” page 5–3
Procedure 5-3, “Connect the transformer,” page 5–4
Procedure 5-4, “Connect the cables,” page 5–7
Procedure 5-5, “Set the input drive,” page 5–10
Procedure 5-6, “Connect the transceiver,” page 5–10
Procedure 6-1, “Operate the amplifier,” page 6–1
Procedure 6-2, “Tuning the amplifier,” page 6–6
Procedure 6-3, “Program the memory,” page 6–10
Procedure 7-1, “Set up to operate from a PC,” page 7–2
Procedure 8-1, “Clean the amplifier,” page 8–1
Procedure 8-2, “Retune the amplifier,” page 8–2
Procedure 8-3, “Replace the tube and fuses,” page 8–4
Procedure 8-4, “Upgrade firmware on the primary board,” page 8–5
Procedure 8-5, “Upgrade firmware on the secondary boards,” page 8–8
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List of Procedures
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1 Introduction
1.1
1.2
1.3
1.4
1.5
Product Description 1–1
Product Capabilities 1–2
Safety Considerations 1–2
Related Products 1–3
Assistance 1–4
Congratulations on your purchase of a professional-quality Alpha 9500
HF linear amplifier.
1.1 Product Description
The ALPHA 9500 (see Figure 1-1) is a self-contained auto-tune HF linear
power amplifier. It is capable of continuous operation at 1500 W peak
power output on single sideband (SSB), keyed continuous wave (CW),
slow-scan television (SSTV), radioteletype (RTTY), digital modes or
FM, with no time limit.
With proper installation and care, you can expect to enjoy your amateur
radio hobby with this amplifier for many years to come.
!
CAUTION
CAUTION! Study this manual carefully before operating your
amplifier for the first time. In particular, it is extremely important that
you thoroughly review the installation and operation sections. Failure
to do so could result in serious damage not covered under warranty.
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Introduction
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Figure 1-1 ALPHA 9500
1.2 Product Capabilities
Product capabilities include:
• Continuous RF output. The ALPHA 9500 is capable of 1.5 kW
continuous RF output on all commonly used modes and on any
authorized amateur frequency from 1.8 to 29.7 MHz (other than the
60-MHz band).
• Compatibility with popular amateur transceivers and exciters. The
ALPHA 9500 requires approximately 50-65 W peak RF drive for
1.5-kW output.
• Capable of full CW break-in, QSK, and all digital modes when used
with any appropriate transceiver.
• Built-in protective functions. The control system incorporates
protective functions that minimize the probability of accidental
damage to the amplifier or its power tubes. In most cases, when one
of the protective functions is tripped, the amplifier goes to standby.
• USB and serial interface allow for remote operations, diagnostics,
and firmware upgrades.
1.3 Safety Considerations
• Locate the ALPHA 9500 where there is good air circulation all
around and on top of the cabinet. The unit may become hot during
operation.
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Alpha 9500 HF Linear Amplifier Operating Manual
Introduction
• Use proper lifting techniques and two people when moving the
ALPHA 9500. The ALPHA 9500 weighs approximately 69 pounds
when the transformer is installed.
• Although the ALPHA 9500 meets international safety standards and
FCC regulations, remember that the equipment works with high
voltages that can be LETHAL!
This operating manual holds information, cautions, and warnings that you
must follow to ensure safe installation and operation. Read Chapter 1
before attempting to unpack or operate the ALPHA 9500. Failure to
perform procedures properly may result in amplifier damage, fire hazard,
or electric shock.
It is particularly important that you:
• Never open the amplifier case without unplugging the unit from the
wall outlet.
• Never stick objects into holes in the case.
• Never touch an antenna during transmission.
• Never attempt to turn on the amplifier without the cover securely in
place (all attachment screws reinserted).
• Never turn the amplifier back on after a hard fault without waiting at
least 20 seconds.
• Never press the ON (AMP) button after the amplifier faults to power
off.
• Never allow liquids to enter the amplifier through the cover holes.
• Never cover or obscure the exhaust holes in the cover of the amp.
1.4 Related Products
Other Alpha products available to enhance your use of the ALPHA 9500
include:
• ALPHA 2100 full-1500 W-rated 50-ohm dummy loads
• ALPHA 4500 series SWR meters and wattmeters
For more information, go to www.alpharadioproducts.com or call 303473-9232.
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Alpha 9500 HF Linear Amplifier Operating Manual
Introduction
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1
1.5 Assistance
Technical assistance from Alpha Radio Products is available from several
sources.
• Go to our website at www.alpharadioproducts.com and click
Support. On this site you can get the following assistance:
• FAQs
• Legacy equipment information
• Manuals
• Repair information
• Software downloads
• Tech tips
• Technical support
• E-mail us at [email protected].
• Fax us at 303-473-9660.
• Phone us at 303-473-9232.
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2 Amplifier Components
2.1 Cathode (Input-Match) Board 2–2
2.2 Center-Partition Board 2–3
2.3 Connections 2–3
2.4 Controls and Display 2–3
2.5 Display Board 2–5
2.6 Firmware 2–5
2.7 Master-Control Board 2–6
2.8 Output-Tank Circuit 2–6
2.9 Power Supply 2–7
2.10 Tube and Tube Deck 2–8
The ALPHA 9500 uses a single 3CX1500 (8877) high-mu external-anode
triode ceramic tube for amplification. The main power supply is an
unregulated transformer/rectifier/capacitor power supply for the highvoltage (HV) and heater circuits. All other power supplies are regulated.
The biasing and tank circuits are similar in most respects to those of the
ALPHA 9500’s predecessor, the ALPHA 77. The unit has thoroughly
modern computer-controlled power supply and control circuitry.
Extensive safety measures protect the amplifier against most off-nominal
conditions. It has USB and RS-232 interfaces to aid in remote operation.
All front-panel features are accessible via these interfaces.
There are six main circuit boards in the amplifier. Communications
among these is via an I2C bus.
The amplifier front and back are shown below (see Figure 2-1 and
Figure 2-2). Amplifier components are listed alphabetically and described
below.
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Figure 2-1 Amplifier front and interior
2
Figure 2-2 Amplifier back
2.1 Cathode (Input-Match) Board
The cathode board, housed in the tube deck, consists of a set of Pi filters
controlled by a set of five relays that are enabled based on the band-switch
setting.
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2.2 Center-Partition Board
The center-partition board contains the RF decoupling circuit on the B+
line as well as the crowbar safety circuit. When you remove the top cover
of the ALPHA 9500, the spring metal of this safety device shorts out the
B+ line.
2.3 Connections
When the ALPHA 9500 is powered up, it measures the line voltage and
chooses, then sets the appropriate tap setting for the transformer primary.
After it is powered up, it does not reset the tap. The amplifier can be set
to override autotaps election and use any primary tap; it may be useful to
do so if your line voltage is unsteady or on the edge of a tap setting. For
more information, contact ALPHA technical support.
Figure 2-3 Primary connections
2.4 Controls and Display
The ALPHA 9500 controls enable you to adjust and monitor the amplifier
as needed (see Figure 2-4).
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IMPORTANT
Note that the front panel has, in the upper-right corner, a 7-segment
LED display (so named because one can, by individually turning on
or off each of just 7 simple bars, display any single digit 0 to 9). The
display contains 4 such digits.
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The buttons below the display control what kind of value is displayed:
FLT, Fwd, Ig, Ip, SWR, or Vp.
Figure 2-4 Amplifier controls
RF Power kW
BAND
0
0.1
0.3
0.6
1.0
1.5
2.5
SWR
1
1.8
3.5
7
10
14
18
21
24
1.5
2
3
>10
100
150
Grid Current mA
28
0
SEGMENT
50
Plate Current Amps
0
1
2
3
4
1.0
1.5
Plate Voltage kV
5
0
MEMORY
1
2
3
4
Fwd
Ip
Vp
Ig
DIM
SND
SWR
FLT
PEP
DEL
ON
ON/OFF
AMP
ANT SEL
Gain
10
SAVE
TUNE
RCL
DEF
1
2
AUTO
LOAD
ALPHA
ANTENNA SELECT
1
2
3
30
50
9500
OPER
MICROPROCESSOR CONTROLLED HF LINEAR AMPLIFIER
STBY
4
Table 2-1 Amplifier Buttons (listed alphabetically)
Button
Purpose
ANTENNA SELECT
Determines which one or two of the four antenna output ports to use.
BAND
Selects an amateur band, designated in megahertz (MHz).
DEL
Displays the delivered power from the amplifier to the selected antenna
port in watts (W).
DIM
Controls the brightness of the display LEDs.
FLT
Sets the 7-segment display to show the last fault. Also loads new
firmware.
Fwd
Sets the 7-segment display to show forward power in W.
GAIN
Displays the gain in decibels (dB).
GRID CURRENT
Displays the grid current in milliamperes (mA).
Ig
Sets the 7-segment display to show grid current in mA.
Ip
Sets the 7-segment display to show plate current in mA.
LOAD
Controls the load capacitor.
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Amplifier Components
Table 2-1 Amplifier Buttons (listed alphabetically)
Button
Purpose
MEMORY
Selects one of three sets of segment memories:
2
• DEF — factory-default settings and user memories
• 1 or 2
• AUTO — autotune
ON (AMP)
Turns the amplifier tube and voltage on.
ON/OFF (ANT SEL)
Turns the antenna select on; the amplifier tube is not on.
OPER
Sets the amplifier to the operate position.
PEP
Toggles between PEP mode and carrier/tune mode.
PLATE CURRENT meter
Displays the plate current in milliamperes (mA).
PLATE VOLTAGE meter
Displays the plate voltage in volts (V).
RCL
(Currently nonfunctional)
RF POWER kW meter
Displays the forward power in W.
SAVE
Saves the current settings.
SEGMENT
Selects different frequencies within each band.
SND
Controls the sound volume (not yet implemented).
STBY
Sets the amplifier to standby (bypass).
SWR meter
Sets the 7-segment display to show SWR.
TUNE (UP or DOWN)
Controls the tune capacitor.
Vp
Sets the 7-segment display to show plate voltage in V.
2.5 Display Board
The display board is the largest board in the amplifier and spans the entire
inside front panel. It has three microcontrollers, one each to control the
stepper motors; the LEDs and 7-segment display and push buttons; and
the sound controller.
2.6 Firmware
The ALPHA 9500 firmware revolves around the Inter-IC (I2C) bus,
developed by Philips for the control of medium-to-high-scale consumer
electronics. This bus allows a master controller to communicate with a
number of slaves.
A single master communicates rapidly and bidirectionally with a number
of slaves, each of which performs a subset of the task required to make an
operational amplifier. Each slave is independently addressable.
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The time for the master to cycle through one round of communications
with all slaves and perform its own tasks defines the natural “heartbeat”
for the amplifier. This heartbeat is 10 ms, which is faster than the response
time of the human eye.
2
You can upgrade the master firmware via a serial or USB connection to a
Microsoft Windows PC. For information, see 8, “Maintaining and
Upgrading the Amplifier,” page 8–1.
2.7 Master-Control Board
The master-control board is the heart of the amplifier. It is based around
a PIC microcontroller, the master of the I2C bus. This microcontroller
communicates with each controller on the other boards in the amplifier. It
is used to monitor all the critical voltages and currents in the amplifier, as
well as the input power and output forward and reflected power. It uses
these converted values to control the amplifier’s operation and to send
data to the front panel, so that the correct LEDs are lit and the stepper
motors move to the correct positions. A standard 9-pin RS-232 serial port
is provided for control and monitoring and is found on the back of the
ALPHA 9500. A USB port is also provided. Either port may be used, but
only one may be active at any one time.
The amplifier automatically senses when a PC is attached to the USB port,
and uses that port. If nothing is connected to the USB, the amplifier
automatically switches back to the RS-232 serial port.
2.8 Output-Tank Circuit
The output-tank circuit provides reliable high-efficiency, low-distortion
performance in a very compact volume. The basic topology is “pi-L”,
which provides harmonic attenuation adequate to meet the requirements
of all countries globally that permit power outputs of 1500 W.
Band switching is under automatic control, accomplished by a 4-wafer
band switch. These wafers are used as multifunction tap selectors, which
simultaneously select band taps on the inductors and include varying
amounts of capacitance to provide band spread on the tune and load
capacitors. The wafers are in the RF tank area. The band-switch position
is controlled by a stepper motor in the front subchassis.
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Amplifier Components
2.9 Power Supply
The power supply has two major sections: a switch-mode supply for the
logic circuitry and a conventional transformer supply for all other
voltages.
When the amplifier is plugged into the AC line, the switch-mode supply
is always on and all the microprocessors are active. It is usual for some of
the front panel LEDs to blink momentarily when the unit is first plugged
in.
The remaining voltages are produced by the mains and HV boards,
described below.
Mains Board
Figure 2-5 Mains board
Power-supply functions are split between the mains board and the HV
board. The mains board deals mostly with the primary side of the
transformer. The various taps for the transformer primary are routed
through this board and so is the AC line input. Relays on the mains board
connect the AC line to the appropriate taps on the transformer primary.
When the ON (AMP) button is pressed, the microprocessor on the mains
board samples the line voltage and determines which tap to select. That
voltage tap remains selected until the amplifier is turned off, and does not
change even if the line voltage fluctuates.
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If you install your amplifier in a location where the line voltage is not
steady, you can force the tap selection via the serial or USB port. For
information on how to force tap selection, contact ALPHA technical
support.
2
Also on the mains board is a step-start circuit. This circuit consists of a
relay and a resistor, which are time-sequenced to limit the inrush current
into the amplifier when it is first turned on.
HV Board
The main high voltage for the amplifier is created on the HV board using
a full-wave bridge rectifier and a bank of capacitors. This power supply
has two 10-ohm resistors, one in the positive (B+) lead and one in the
negative return to the tube cathode. This combination of resistors limits
the surge current in the case of a B+ arc. The voltage across the resistor in
the negative return monitors tube plate current in the control board. This
voltage also generates the hard-fault condition.
When the power-supply current exceeds about 2.5 amps, a latching relay
opens the coil circuit of the mains tap relays on the mains board, causing
the amplifier to go to the power-off state. This hard-fault circuit operates
independently of microprocessor control.
All power-supply filter capacitors on this board have bleeder resistors that
discharge the capacitors in less than 60 seconds. If you must work on this
board, confirm the discharged condition with a voltmeter, due to the
remote possibility of bleeder resistor failure.
2.10 Tube and Tube Deck
The ALPHA 9500 uses a single 8877 triode tube. The tube operates well
within its published ratings. It is operated in Class AB1, with a plate
voltage of 3300 V (nominal, full output, key down) and a cathode voltage
of 9.4 V.
The tube deck is a mechanical assembly that houses the tube socket and
the cathode (or input match) printed circuit board (PCB).
A temperature sensor mounted on the cathode PCB measures the
temperature of the air immediately below the tube socket. This
temperature measurement is used by the master controller as part of the
fault-detection software.
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3 Installation Overview
3.1
3.2
3.3
3.4
3.5
3.6
3.7
Prepare Your Station 3–1
Unpack the Amplifier and Transformer 3–2
Install the Transformer 3–2
Connect the Transformer 3–2
Connect the Cables 3–3
Set the Input Drive 3–3
Connect the Transceiver 3–3
This chapter provides a brief overview of the ALPHA 9500 installation
process.
Do you already have a well-designed shack and have you used an
amplifier before?
• If YES, review the items below to ensure that you consider all the
critical items for proper installation and operation.
• If NO, skip this chapter and follow the detailed instructions starting
in Chapter 4, “Preparing Your Station.”
If you have installation questions, call Alpha Radio Products at 303-4739232.
3.1 Prepare Your Station
SEE . . .
Section 4.1, “Prepare Your Station,” page 4–1
Step 1
Provide 220 VAC power.
Step 2
Provide proper airflow.
Step 3
Ready your antenna for 1500 W.
Step 4
Provide adequate RF cabling.
Step 5
Provide surge protection.
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3.2 Unpack the Amplifier and Transformer
SEE . . .
3
Section 5.1, “Unpack the Amplifier and Transformer,” page 5–1
Step 1
Remove the amplifier and transformer from their cartons.
Step 2
Inspect the amplifier and transformer for shipping damage.
Step 3
Remove the blower screw from the bottom of the amplifier.
3.3 Install the Transformer
SEE . . .
Section 5.2, “Install the Transformer,” page 5–3
Step 1
Position the amplifier on a flat surface, at or near where it is to be used,
with plenty of room for you to work.
Step 2
Slowly move the amplifier and transformer together, aligning the nuts on
the transformer with the screw holes on the bottom of the amplifier.
Step 3
Secure the transformer into place from the bottom of the amplifier by
inserting the supplied bolts (1/4/20 ½-inch hex bolts) with ¼-inch
washers through the four clearance holes in the chassis and into the nuts
in the transformer base.
Step 4
Carefully rotate the amplifier back to its standard orientation.
3.4 Connect the Transformer
SEE . . .
Page 3–2
Section 5.3, “Connect the Transformer,” page 5–4
Step 1
Connect the transformer to the chassis.
Step 2
Connect the transformer to the amplifier’s high-voltage (HV) board (the
lower of the two boards).
Step 3
Connect the transformer to the amplifier’s mains board (the upper of the
two boards).
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3.5 Connect the Cables
SEE . . .
Section 5.4, “Connect the Cables,” page 5–7
3
Step 1
Connect the power cord.
Step 2
Adjust the 8877 tube and exhaust chimney.
Step 3
Replace the amplifier cover and all attachment screws.
Step 4
Place the amplifier in its operating position on a stable surface with
sufficient space to the rear, sides, and top to allow good air flow and safe
placement of cables.
Step 5
Connect the amplifier RF INPUT to the transceiver RF OUTPUT.
Step 6
Connect the amplifier RF OUTPUT to the antenna.
Step 7
Connect the transceiver (T/R) control cable to the amplifier.
3.6 Set the Input Drive
SEE . . .
Step 1
Section 5.5, “Set the Input Drive,” page 5–10
[need info]
3.7 Connect the Transceiver
SEE . . .
Section 5.6, “Connect the Transceiver,” page 5–10
Step 1
Connect the transceiver.
Step 2
(Optional) Enable the transceiver automatic antenna tuner.
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4 Preparing Your Station
4.1 Prepare Your Station 4–1
4.2 Limitations of Operation at 90–130 VAC 4–4
4.1 Prepare Your Station
The ALPHA 9500 is capable of dramatically improving the performance
of your amateur station. It is important that you observe good engineering
practices to achieve all the benefits of such a station in a safe and reliable
manner.
This chapter provides a few important operational considerations. We
recommend that you also consult a good source of general information
such as the latest Amateur Radio Relay League (ARRL) Handbook for
Radio Amateurs, especially if this is the first high-power amplifier that
you have used.
Procedure 4-1 Prepare your station
Step 1
Provide 220 VAC power.
The amplifier runs best when powered by a 200–240 VAC circuit. If you
do not have a 220 VAC outlet in your station, have a licensed electrical
contractor install one. A minimum of a 20 A capacity is required. A 20-A
breaker on your 220-V circuit is sufficient.
When you size the circuit, be sure to include the current drawn by other
equipment that may be on the same circuit.
Select a location for the outlet as close as possible to where you expect to
operate the amplifier. If you are not sure or contemplate moving the
amplifier, consider installing two outlets.
There are many styles of power plugs, some of which are countryspecific. For this reason, the amplifier is not shipped with a plug. Ask your
contractor for two or three matching plugs during installation.
Ask the contractor to measure the voltage and record it for reference.
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Although the amplifier can run when connected to a 110 VAC outlet, you
WILL NOT achieve full-legal-limit output in this case. Rather, you
should not expect more than 1000 W output. For more information on the
limitations of operation when connected to a 110 VAC outlet, see 4.2,
“Limitations of Operation at 90–130 VAC,” page 4–4.
Note that, when the amplifier is plugged in and turned on, it is normal to
hear the capacitors and band-switch zero themselves and a slight “clunk”
as the transformer comes up to full load.
Step 2
Provide proper airflow.
It is critical that airflow around the amplifier remain unimpeded at all
times and that the top of the amplifier remain clear of any restrictions.
Maintain at least 3 inches of clearance around the amplifier to allow for
unobstructed airflow (see Figure 4-1).
Figure 4-1 Minimum clearance for proper airflow
If you are mounting the amplifier in a console, ensure that the exhaust air
is properly and fully removed from the console. If outlet air is drawn back
into the amplifier air intake and recirculated, the amplifier gets hotter and
hotter, resulting in degraded performance or even failure. If you are
designing your own console, consider putting in additional fans and/or
ducting to deal with waste heat.
Minimize the possibility of dust or other contamination getting drawn into
or falling on the amplifier. Periodically (at least annually) clean the dust
out of the amplifier, paying particular attention to the tube fins. We
recommend the use of compressed air for dust removal.
Step 3
Page 4–2
Ready your antenna for 1500 W.
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Preparing Your Station
Many antennas that are suitable for general use are unsuited for operation
with a full 1500 W of power. At this power level in a 50-ohm circuit, the
RMS current is 5.5A and the peak RF voltage is 387 V. With a 2:1 SWR,
these values double to 11 A and 775 V. The actual voltage and current at
various points in or on your antenna may actually be many times these
values.
On a simple dipole with sharp wire ends, corona (localized ionization) can
easily occur. Corona can (and has!) led to fire in nearby objects. Traps in
beams and verticals can heat up significantly during high power
operation. Instances of melting or flashover of traps have occurred in
many installations where insufficient thought has been given to their
ratings.
If you have deployed an antenna for a long period of time, take it down
now for inspection. Double-up on insulators and replace any that are
cracked or show signs of tracking. If there is any chance of people,
animals, or objects coming close to the antenna, move it higher or place
barriers to prevent access. Adjust the antenna for minimum SWR in your
favorite part of any band.
Step 4
Provide adequate RF cabling.
The importance of a well-constructed feed-line system cannot be
overstated.
After all, the purpose of the amplifier is to provide approximately 2 S
units (12+ dB) of improvement in your radiated signal. All too often,
however, installation problems result where cheap, poor, or underrated
coax and connectors are used. These often are responsible for at least one
S unit of degradation. In other words, you could have bought a 375 W
amplifier and achieved the same radiated signal by buying good-quality
feed-line components!
Use the lowest-loss 50-ohm coaxial cable that you can obtain. Use new,
clean connectors installed according to the manufacturer’s
recommendation. Clean the connectors after soldering them and before
mating them with the amplifier. Remove any excess solder and fragments
of braid and the like from the connector. Never use old coax, which may
have had moisture penetrate under the jacket.
Run the coax in straight lines as much as possible. Support it frequently
using noncompressive clips so that it does not hang or stretch under its
own weight.
Avoid sharp bends (most manufacturers specify a minimum bend radius
for their product). Ensure that the connection from feedline to antenna is
waterproof. Provide for disconnection of the feedline when it is not in use
to protect against damage caused by power surges and lightning strikes,
which are not covered under the amplifier warranty.
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NOTE: The FCC requires users to check their installations for
compliance with published values for allowable exposure to RF fields.
This information is available in ARRL publications, FCC printed rules,
and on the web. We strongly recommend that you do this for any
installation, both fixed and at an expedition or contest site.
If you have any questions regarding engineering your amplifier into
your amateur radio station, visit our technical-support website at
www.alpharadioproducts.com.
4
Step 5
Provide surge protection.
Induced energy from nearby electrical storms or other power transients
may damage components. Such damage is not covered under warranty. It
is therefore important to use a good lightning arrestor. However the only
lightning-proof solution available is to disconnect antenna feedlines and
AC power when the equipment is not in use.
NOTE: Whenever the amplifier is online — either off, in standby
(STBY), or in warm-up with the WAIT LED lighted — the amplifier is
bypassed and the exciter is connected directly to the antenna. The
throughput limit in all cases is 1500 W.
4.2 Limitations of Operation at 90–130 VAC
Electrical-power equipment draws twice as much primary current from
120 V mains as from 240-V mains. Therefore, if you operate the
ALPHA 9500 on typical 120 V/20 A household circuit without exceeding
the 20-A circuit rating, you limit maximum peak power output to about
600–1000 W.
Maximum possible RF output power for any particular primary AC
voltage and current capacity may be estimated as:
Po max = (Vline x Iline) / 2.3
(4-1)
For example, if the amplifier operates from a circuit that delivers 115
VAC at a maximum current of 20 A with no other loads connected to the
circuit, maximum peak RF output possible without tripping the 20-A
breaker (or fuse) is approximately:
Po max = (115 V x 20 A) / 2.3 = 2300/2.3 = 1000 W
(4-2)
If the same circuit also supplies a transceiver drawing peak line current of
5 A and a lamp drawing 1 A, only 20-5-1 = 14 A is available for the
amplifier and maximum possible output is about:
Po max = (115 V x 14 A) /2.3 = 1610/2.3 = 700 W
(4-3)
Following are some considerations at the high and low ends of this
voltage range that are rarely encountered.
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Preparing Your Station
If your line voltage is below 110 V under load, do not expect to be able
to get 1500 W output (see Table 4-1).
Table 4-1 Amplifier behavior with nonstandard line voltages
Line voltage
Expected behavior
Low: 90–110 V
Power outputs above 1000 W are not expected.
Normal: 110–130 V 1500 W PEP operation (CW or SSB) may be
possible if your AC line service has sufficient
current capacity (30-A circuit recommended).
However, 1500 W continuous should not be
expected.
High: >250 V
NOTE
Lifetime of the tubes may be reduced. Ask your
utility company if they can reduce your line
voltage. If this is not possible, consider placing
your own step-down transformer in line between
the AC outlet and the amplifier. A transformer
with at least 4-kVA rating is required, due to the
nature of the current waveform in the primary.
Another choice for voltage control, a ferroresonant
voltage regulator, is an expensive solution, but is a
good way to stabilize primary voltage.
If you intend to operate the amplifier at ~120 V or if other equipment
draws current from the same circuit as the amplifier, the following
apply:
1. If you replace the factory-shipped 20 A/250 V fuses with 25 A/250
V “slo-blo” fuses (for line voltages of less than 100 V), be aware
that the higher current at the lower voltage significantly warms the
amplifier’s power cord. The cord (as well as fuse holders and
some internal connectors) are operating near their maximum
ratings due to the current demand at lower voltages.
2. Ensure that the AC cord is not coiled too tightly or placed where
normal air flow is restricted, causing it to overheat.
3. You must change the two lower 2A fuses on the rear panel to 5A
fuses to allow for the increased in-rush current.
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5 Setting Up the Amplifier
5.1
5.2
5.3
5.4
5.5
5.6
IMPORTANT
!
Unpack the Amplifier and Transformer 5–1
Install the Transformer 5–3
Connect the Transformer 5–4
Connect the Cables 5–7
Set the Input Drive 5–10
Connect the Transceiver 5–10
The ALPHA 9500 is extremely easy to set up, tune, operate, and
maintain. However, failure to carry out each procedure exactly as
described in this manual is likely to lead to amplifier damage, which
is not covered under warranty. Damage to other station equipment
may also result.
Proceed slowly throughout these procedures to avoid bumping and
damaging adjacent wires, connectors, and components.
5.1 Unpack the Amplifier and Transformer
Procedure 5-1 Unpack the amplifier and transformer
Step 1
Remove the amplifier and transformer from their cartons.
The ALPHA 9500 ships in two heavy-duty cardboard cartons, each
mounted on a wooden pallet and strapped down for secure shipping. The
amplifier weighs 39 lb (18 kg); the transformer weighs 43 lb (20 kg).
1a Remove the strap securing the two boxes to the pallet.
1b Inspect the boxes for shipping damage.
1c Unpack the cartons.
1d Retain the pallet and cartons in the unlikely event that you need to
ship the unit later.
Step 2
Inspect the amplifier and transformer for shipping damage.
If you find damage, call Alpha Radio Products at 303-473-9232.
Step 3
Remove the blower screw from the bottom of the amplifier.
3a Place the amplifier on the bench or desk where it is to be used.
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3b Remove the cover screws (Figure 5-1) and the cover.
Figure 5-1 Cover screws
5
3c Rotate the amplifier onto its right hand side.
3d While looking at the bottom, locate and remove the screw (labeled
BLOWER SCREW, Figure 5-2) that holds the blower in place
during shipping.
Figure 5-2 Blower screw
NOTE: Before shipping, reinsert the screw to prevent damage to the
blower.
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Setting Up the Amplifier
5.2 Install the Transformer
NOTE
• The transformer is very heavy. When moving it, use due caution
and handle only by the lifting handle.
• The extra piece of wood shipped with the amplifier is the
transformer shim, which was cut to specific dimensions to aid in
this installation.
• Do not over-tighten the screws that hold the transformer in place,
as doing so may cause excessive vibrations or noise.
• If you move the amplifier, even if only from one site to another
locally, remove the transformer first to avoid the possibility of
damage.
Procedure 5-2 Install the transformer
Step 1
Position the amplifier on a flat surface, at or near where it is to be used,
with plenty of room for you to work.
Installing the amplifier on a tilt so far that the transformer is cantilevered
or hangs out to any degree causes the chassis to distort, which may affect
a number of things, from the alignment of screw holes on the top cover to
the band-switch alignment and tension.
Step 2
Slowly move the amplifier and transformer together, aligning the nuts on
the transformer with the screw holes on the bottom of the amplifier.
Figure 5-3 Moving amplifier and transformer together
Step 3
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Secure the transformer into place from the bottom of the amplifier by
inserting the supplied bolts (1/4/20 ½-inch hex bolts) with ¼-inch
washers through the four clearance holes in the chassis and into the nuts
in the transformer base.
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Figure 5-4 Securing transformer
5
Step 4
Carefully rotate the amplifier back to its standard orientation.
5.3 Connect the Transformer
Procedure 5-3 Connect the transformer
Step 1
Connect the transformer to the chassis.
Figure 5-5 Connecting transformer to chassis
1a Align the transformer’s Molex plug with the connector at the back of
the amplifier.
1b Push to connect them so that they are fully mated.
Step 2
Connect the transformer to the amplifier’s high-voltage (HV) board (the
lower of the two boards).
2a Locate the transformer’s 7-pin HV connector. Move the 2-pin mains
connector out of the way as needed to do so.
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Figure 5-6 Transformer’s 7-pin HV connector (top) and 2-pin mains
connector (bottom)
5
2b Carefully route the transformer’s HV connector below all of the other
bundled wires.
NOTE:
• Do not bump or bend components on either board.
• Do not allow the HV wiring to touch any of the upper circuit board.
Figure 5-7 Routing transformer’s HV connector
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2c Align the transformer’s HV connector with the amplifier’s HV board
connector, with all pins in their appropriate slots, then gently but
firmly push the connectors together so that they are fully mated.
Figure 5-8 Connecting transformer to the HV board
5
Step 3
Connect the transformer to the amplifier’s mains board (the upper of the
two boards).
3a Locate the transformer’s 2-pin mains-board connector.
Figure 5-9 Transformer’s 2-pin mains-board connector
3b Locate the respective 2-pin connector on the amplifier’s mains board.
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3c Align the connectors with both pins in their appropriate slots, then
gently but firmly push the connectors together so that they are fully
mated.
Figure 5-10 Connecting transformer to mains board
5
5.4 Connect the Cables
Procedure 5-4 Connect the cables
Step 1
Connect the power cord.
!
WARNING
WARNING! To avoid the hazard of a potentially fatal electric shock
and/or severe damage to the ALPHA 9500 and other equipment:
• ALWAYS use an AC plug that is appropriate for the primary mains
voltage, current rating, and configuration.
• ALWAYS use grounding type AC connectors that conform to local codes.
• NEVER use 120-V-type plugs to connect to power receptacles for
190–250 V circuits.
• ALWAYS connect ALL station equipment to a good common ground.
Failure to do so may allow RF feedback to leak into the transceiver and
cause severe signal distortion.
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55
!
Alpha Radio Products
Product Release 1
CAUTION
CAUTION! We strongly recommend that you operate the amplifier
on 240 VAC current. If you choose not to heed this recommendation,
see a discussion of the limitations of doing so in 4.2, “Limitations of
Operation at 90–130 VAC,” page 4–4.
1a Connect the green wire in the amplifier power cable only to the AC
mains safety ground (or to neutral, as may be necessary with a 240-V
circuit configured 120V-N-120V without a separate ground,
commonly found in the US).
5
1b Connect the black-and-white power cord wires to the two hot wires
of the AC source. Either wire may be connected to either side of the
line. For best results, use a dedicated 200–240 V branch circuit of #10
AWG copper wire or equivalent, rated at 20 A, to feed the amplifier.
1c Connect the ground stud with wing nut on the rear of the chassis to a
good RF earth ground, such as a copper water pipe or driven rod, via
heavy copper braid or strap.
Step 2
Adjust the 8877 tube and exhaust chimney.
2a Ensure that the 8877 tube is firmly seated in its socket.
2b Ensure that the silicon-rubber exhaust chimney is straight and that it
is fully and correctly installed so that the bottom of the chimney is
firmly against the tube deck and completely covers the airflow
opening in the deck. Tube cooling exhaust must exit only through the
tube anode fins; it must not be allowed to escape outside them.
Failure to ensure proper cooling airflow may result in tube damage or
destruction, which is not covered under warranty.
2c Ensure that the anode connector is tightly clamped to the 8877 tube.
Step 3
Replace the amplifier cover and all attachment screws.
Use only the 6-32 screws supplied with the amplifier and do not tighten
any of the screws until all are started.
!
WARNING
WARNING! Do not attempt to operate the amplifier with the cover
removed or placed on the unit without the attachment screws. Doing
so damages the ALPHA 9500 and may also cause injury or death to
the operator.
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Setting Up the Amplifier
Step 4
Place the amplifier in its operating position on a stable surface with
sufficient space to the rear, sides, and top to allow good air flow and safe
placement of cables.
Step 5
Connect the amplifier RF INPUT to the transceiver RF OUTPUT.
Use 50-ohm coaxial cable-RG-58C/U or equivalent. A 6-ft. cable is
supplied for this purpose.
Step 6
Connect the amplifier RF OUTPUT to the antenna.
Use RG-8A/U, RG-213/U, or equivalent high-quality cable with a PL-259
UHF-type plug on the amplifier end. Do not use RG8X cable, because it
is not rated for 1500 W.
Step 7
Connect the transceiver (T/R) control cable to the amplifier.
HINT: The T/R control cable is also known as the keying cable.
The amplifier has a full break-in vacuum relay QSK system that requires
only the normal interconnection when used with a modern QSK
transceiver. The amplifier requires a contact closure (short circuit) on
transmit from its RELAY jack center pin to the chassis. This function is
supplied by the transceiver, usually from a dedicated relay that is
normally open in receive and closed in transmit.
7a Use shielded wire for the T/R control cable. Fit the amplifier end with
a common phono (RCA-type) plug and the transceiver end with a
suitable connector.
7b Ensure that the T/R relay contact closes. Protection circuitry prevents
hot-switching when RF drive is applied. Modern transceivers have
the proper time delay between key-up and the start of the transmitted
signal to allow the amplifier to follow the CW keying.
If you suspect a T/R timing problem:
1. Connect the CW keyer to the RELAY jack on the amplifier.
2. Connect a cable from KEY OUT on the amplifier to the keying
input of the transmitter.
3. Ground the key cable (they should key up).
4. Apply power from the transmitter. The amplifier should respond
with power out to the antenna.
NOTE: The amplifier does not generate or use Automatic Level
Control (ALC) voltages to control an exciter.
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5.5 Set the Input Drive
You must set the transceiver output power properly. Virtually all damage
to date has resulted directly from severe overdrive. The amplifier requires
50-W drive for full rated output.
Damage caused by applying several-times-rated drive power to the
amplifier is not covered under warranty. Fortunately, most modern
transceivers maintain quite consistent output from band-to-band and
mode-to-mode when set up properly.
Procedure 5-5 Set the input drive
5
Step 1
Place the amplifier in standby mode on the desired band.
Step 2
Start with the minimum power and then adjust the transceiver output to
around 20 W. You can read the power on the 7-segment display.
!
CAUTION
CAUTION! It is not sufficient to set only the transceiver POWER or
RF PWR control. Several popular transceivers can generate RF
spikes of 200–300 W. Control of these spikes typically is done with a
knob labeled DRIVE (IC-781, FT-1000) or PROCESSOR OUT (TS940, TS-950). On SSB, when speech processing is not used, adjust
the MIC or MIKE controls. See the user manual for your particular
transceiver.
5.6 Connect the Transceiver
Procedure 5-6 Connect the transceiver
Step 1
Connect the transceiver.
The following is a list of popular transceivers and considerations for their
connection to the amplifier. For advice on other transceivers, contact
Alpha Radio Products as described in Chapter 1, “Introduction.”
Table 5-1 Popular transceivers
Transceiver
Connection and keying information
Icom
RF —
T/R — Connection with the “Send” jack. For
information, see the transceiver user manual.
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Setting Up the Amplifier
Table 5-1 Popular transceivers
Transceiver
Connection and keying information
Kenwood
RF —
T/R — For information on connecting to external
amplifiers, see the transceiver user manual.
Yaesu
RF —
T/R — Connection with the RCA “TX GND” connector
and/or DIN “Band Data” connector. For information,
see the transceiver user manual.
Older
transceivers
Step 2
For information on connecting to external amplifiers,
see the transceiver user manual.
(Optional) Enable the transceiver automatic antenna tuner.
Many popular transceivers have built-in antenna tuners. Although a tuner
is not usually needed when driving your amplifier, you may use it with
care through the amplifier.
For instructions, see the transceiver user manual.
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6 Operating the Amplifier
6.1
6.2
6.3
6.4
6.5
Operate the Amplifier 6–1
(Optional) Set Up to Operate from a PC 6–3
Put the Amplifier into the Desired State 6–3
Tune the Amplifier 6–5
Program the Amplifier Memory 6–9
Before you operate the amplifier, follow procedures in the previous
chapters to install it, set it up, tune it, and save the tune/load/antenna
values.
6.1 Operate the Amplifier
Procedure 6-1 Operate the amplifier
Step 1
Power up the amplifier by pressing one of the amplifier’s two ON buttons:
• ON/OFF (ANT SEL) button
This provides initial power to the metering, band, and segmentselection circuits, which turns on the wattmeter and the antennaselection functionality (ON1 setting). When you turn on the amplifier
with this and pass RF through the amplifier, the amplifier follows
your RF signal by going to the last antenna for that frequency,
moving the band switch into position for that band, and measuring the
throughput power, SWR of the antenna, and so forth. You can pass
up to 1500 W through the amplifier in bypass or the ON1 setting.
• ON (AMP) button
This button duplicates the functions described above, and also applies
high voltage to the tube. The amplifier begins its warmup countdown
sequence and the 7-segment display shows the seconds remaining in
the countdown. The STBY switch light blinks.
Step 2
During the countdown and at any other time, display amplifier parameters
as desired by pressing the associated button that controls the 7-segment
display. For information on these buttons, see 2.4, “Controls and
Display,” page 2–3.
During the countdown, be sure to press the Vp button to display the plate
voltage. This should be about 3545 V.
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• If the value is <3300 V, check your outlet, the wiring of the plug, and
the grounding of the equipment in your shack. If you have variable or
unstable power, you can force the amplifier to always choose a
particular tap setting. For information on how to force tap selection,
contact ALPHA technical support.
• If the value is >3800 V, ensure that the correct primary tap is being
selected. If auto-tap-selection is disabled, try enabling it. If the
highest tap is being used, your line voltage is likely >250V; talk to
your power company about reducing it.
To return to the countdown display, press the FLT (Fault) button.
NOTE
During warmup and operation, do not press the MEMORY/AUTO
button. The amplifier always performs automatic frequency detection,
band-tuning, and antenna selection independently from this button.
Rather, use this button to assist with initial tune and load settings as
described in Section 6.4, “Tune the Amplifier,” page 6–5.
Step 3
Push the OPER button and select the correct antenna.
Step 4
Key the amplifier by putting the transmitter into transmit mode (State 5:
keyed, no RF).
6
NOTE: For information about amplifier states and what it means to
key the amplifier, see 6.3, “Put the Amplifier into the Desired
State,” page 6–3.
Step 5
Apply RF.
When the amplifier is keyed and RF is applied, the following sequence
occurs automatically:
1. The mains controller on the amplifier counts the frequency and jumps
to the correct band switch position and frequency segment.
2. The antenna is set to the last one used for that frequency on that
memory bank (Default, User 1, or User 2).
3. The tune and load capacitors are set to the saved values for that band
segment.
This is the normal functioning of the amplifier and no other user
intervention is required.
Step 6
Monitor the grid current.
The amplifier operates in Class AB2 when delivering maximum output
power consistent with excellent linearity. A small amount of grid current
flows, which you can monitor via the grid-current bar graph. As overdrive
approaches, grid current increases rapidly and the red grid LEDs become
illuminated.
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Operating the Amplifier
At maximum output and efficiency, the red grid LEDs should not be
illuminated. If they are illuminated before the desired value of plate
current and/or power output is reached, readjust amplifier loading before
continuing.
Step 7
Ensure that exhaust air is detectable from the exit vent holes above the
tube. If exhaust air is not detectable:
7a TURN OFF the amplifier immediately.
7b Ensure that the exhaust chimney is properly positioned over the tube.
7c Power up the amplifier again.
NOTE
If the amplifier faults, it usually resets itself after 4 seconds.
• To reset the amplifier manually if it fails to reset itself, push ON/
AMP and then OPR. (You need not turn the amplifier off.)
• To display the last fault, press the FLT button and view the 7segment display.
• To display the last 15 faults, open the AR9500 PC application that
allows remote control over a serial interface and select the
correct COM port. Select Tools > Get fault log.
To see a complete list of possible faults, see Chapter 9, “Diagnosing
Faults.”
6.2 (Optional) Set Up to Operate from a PC
You can optionally control the ALPHA 9500 completely from the
Microsoft® Windows® AR9500 PC application rather than from the front
panel.
For more information, see Chapter 7, “Operating the Amplifier from a PC
Interface.”
6.3 Put the Amplifier into the Desired State
The ALPHA 9500 can be in one of seven states at any instant. These are
shown in Table 6-1 and described below.
Table 6-1 Amplifier states
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State
Amplifier Status
0
OFF: Amplifier plugged in but OFF
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Table 6-1 Amplifier states
State 0 (OFF)
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State
Amplifier Status
1
ON 1: Amplifier is being used with exciter only. No tube heater
or HV
2
ON 2, warmup: Tube is warming up. HV present.
3
Standby: Tube is ready; amplifier is in bypass mode (exciter
only).
4
Operate, unkeyed: Key-in has not been asserted.
5
Keyed, no RF: Key-in has been asserted, but no RF sensed.
6
Power: Amplifier is keyed and RF has been sensed, amplifier
delivers power.
When the amplifier is first plugged into the AC line supply, it enters State
0. The front panel lights all briefly illuminate, then turn off so that the
entire front panel is dark. If the lights stay on, unplug the AC connector
for a few seconds and plug in again.
In this state, the amplifier has an internal auxiliary 5V power supply that
is on. All the microprocessors are powered up and communicating with
one another. The USB and RS232 ports on the rear of the amplifier are
active.
State 1 (ON 1)
To enter this state from State 0, press the ON/OFF (ANT SEL) button or
send a command from one of the serial interfaces.
Use this mode when you need to access the antenna switch function but
you are using only exciter power. The portions of the front panel display
that are appropriate in this mode are enabled, and others are inhibited.
The internal frequency counter is active, and automatically switches
antennas when you transmit, in the same fashion as when the amplifier is
in State 2 or higher.
Forward power and SWR are indicated on the digital meter and the bar
graphs.
State 2 (ON 2)
To enter this state from State 0 or 1, press the ON AMP button or send a
command from one of the serial interfaces.
The AC line is connected to the primary of the transformer, and all
amplifier voltages are now present, including the high voltage for the tube
plate. When the amplifier enters this state, the stepper motors may turn
briefly. This sounds like a low growl from the amplifier.
A three-minute timer commences, to allow the tube time to warm up. The
amplifier cannot move to a higher state until this timer reaches zero. To
see the number of seconds remaining in the countdown, tap the FLT
button and watch the digital meter.
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Product Release 1
Alpha 9500 HF Linear Amplifier Operating Manual
Operating the Amplifier
We recommend that you check the plate voltage. To do this, tap the Vp
button and watch the digital meter. It should be in the range 3400 to 3650.
State 3 (Standby)
To enter this state from State 2, wait until the three-minute timer reaches
0.
In this mode, the exciter is able to use the antenna, but the amplifier is not
amplifying the signal.
Certain faults cause the amplifier to return to this mode.
State 4 (Operate, unkeyed)
To enter this state from State 3, wait for the amplifier to warm up and
press the OPER button. Or issue the command for the OPER mode from
the serial interface.
The amplifier is fully warmed up, but the key-in line has not been
activated. The tube is biased to a very low current, and the exciter is still
connected to the antenna.
State 5 (Keyed, no RF)
To enter this state from State 4, wait for the key-in line to be shorted to
ground by the exciter.
The input and output relays are activated, and the exciter is now
connected to the input of the tube.
IMPORTANT
!
State 6 (Power)
The phrase “keying the amplifier” throughout this manual means to
move from State 4 to State 5.
To enter this state from State 4 or 5, wait for the amplifier to sense RF.
The tube is biased to its operational condition, and the amplifier measures
the frequency of the RF and attempts to match its operational condition to
the drive frequency and power that it senses.
If the frequency of the input signal indicates that a band change is needed,
the amplifier briefly unkeys to avoid damage to the bandswitch.
In this stage, you cannot activate the antenna selection features. This is
done to avoid hot-switching the relays.
The amplifier is now fully operational and delivering power to the load.
6.4 Tune the Amplifier
The ALPHA 9500 has an autotune feature for tuning to the desired
frequency. You can turn the feature on and off. You might want to turn it
off, for example, if there is heating in the antenna, coax, tuner, or balun
transformer, which might cause the amplifier to unnecessarily keep
tuning. The newest firmware has autotune hunting disabled; however, the
LED is still on, indicating that the autotune feature is still active.
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REMEMBER
Remember
Alpha Radio Products
Product Release 1
If you need to retune, key the amplifier and press the MEMORY/AUTO
button once.
If the amplifier does not retune, with the amplifier keyed, press the TUNE
(down) button once or twice, which forces the amplifier to recheck the
gain and retune.
Procedure 6-2 Tuning the amplifier
Action
Result
Step 1
Set the transceiver to the desired
band/segment frequency. For a list
of frequencies, see Table 6-2,
page 6–9.
Step 2
Set the antenna port to the correct
antenna.
Step 3
Press the MEMORY/AUTO
button to turn on autotune.
Step 4
Apply ~10 W to the amplifier and
wait for the amplifier to finish
autotuning.
The amplifier jumps to the
specified band and autotunes.
Step 5
With the amplifier keyed, slowly
advance the transceiver power.
This is called “walking the amp
up.”
As you increase the power, the
amplifier continues to tune.
Step 6
When you reach the desired output The Save LED blinks on and off
power level, unkey the amplifier
once. The tuning and antenna port
and press the SAVE button once. settings are now associated with
the indicated band/segment.
6
From now on, each time you are in
the User 1 (or User 2) memory, key
the amplifier, and apply RF in that
range of frequencies, the amplifier
jumps to these saved settings.
Step 7
Page 6–6
Repeat the previous steps for all
segments and bands.
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Operating the Amplifier
Action
Step 8
Press the MEMORY/AUTO
button again to turn off autotune.
Step 9
(Optional) Verify the saved
settings by returning to each
frequency and confirming the
power output. Make any necessary
adjustments and save as before.
Step 10
Result
If you get a gain fault (fault 1)
while following this procedure,
assist the autotune as follows:
6
1. Unkey the amplifier so that the
fault clears.
2. Decrease the power.
3. With the MEMORY/AUTO
button pressed, key the
amplifier and press the TUNE
(down) button twice to restart
the autotune.
4. Gradually increase the power.
NOTE:
• The amplifier is tolerant of at least a 3:1 output mismatch at most
frequencies. If you do not save settings for any one of the
segment locations in User 1, the factory-set values are applied
to that location (the Alpha 50 ohm dummy load values that may
or may not be correct for your antenna and your station).
• If you are using a different antenna for one of the bands (for
example, 80 m), the tuneup procedure is the same as above
except that you must choose the antenna port first before keying
the amplifier on that band. Press the correct ANTENNA
SELECT button for the antenna that you wish to use. You are
now ready to tune the amplifier up on 80 m. The amplifier stays
on that antenna port until a band change. If you wish to return to
the same settings, save the settings into memory.
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6
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Action
Step 11
Result
To change the default antenna to a The new antenna port value is now
different port for all User 2
spread across all bands and
memory bank settings:
segments on User 2.
1. Press User 2 so that the
memory light is on.
2. Press the desired antenna port
twice.
3. While the antenna light is
blinking, press the SAVE
button.
Step 12
To listen (and transmit) on two
antennas simultaneously:
1. Press the ANTENNA
SELECT button for the first
desired antenna twice.
Both antenna lights should now be
on and both antennas open for
listening and transmitting.
2. While the light is blinking,
press the button for the second
desired antenna.
NOTE: After you set up your amplifier with reasonable tune and
load settings, do not use the amplifier’s MEMORY/AUTO button.
Small changes in frequency and antenna performance are
handled easily within the amplifier tuning range.
Step 13
To change the center frequency
associated with a particular
segment in User 1 or User 2:
Current is saved to the center of the
chosen segment.
1. Go to the desired frequency
and key the amplifier.
2. While the amplifier is
producing power, press the
desired segment button to
save.
NOTE: Center frequencies for each band must increase in order
from 1 to 5 (segment 1 is the lowest and segment 5 is the highest).
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Alpha 9500 HF Linear Amplifier Operating Manual
Operating the Amplifier
6.5 Program the Amplifier Memory
The ALPHA 9500 has 5 memory settings per band per user (default, User
1, and User 2). Each memory setting holds 3 values: frequency, tune, and
load.
These capacitor settings are made at the factory by tuning into a 50-ohm
load, saving the settings, and migrating them to the appropriate memory
bank. The amplifier is thus set up at the factory so that the memory-bank
tune and load settings across all bands and band segments are appropriate
for 1500-W output into a 50-ohm load on antenna port 4 for User 1 and
User 2.
Antenna port 4 is the default output port for all memories on initialization.
We recommend that you choose antenna port 4 for your primary antenna
on User 1. If no antenna is connected or the wrong port is selected, you
get an SWR fault (Fault 12).
The default memory settings are the only ones that cannot be changed
(except at the factory). They are listed in Table 6-2.
Table 6-2 Factory-set memory settings by band and segment
Band
Seg 1
Seg 2
Seg 3
Seg 4
Seg 5
28
28.20
28.60
29.00
29.40
29.80
24
24.55
24.65
24.75
24.85
24.95
21
21.05
21.15
21.25
21.35
21.45
18
18.05
18.15
18.25
18.35
18.45
14
14.05
14.15
14.25
14.35
14.45
10
10.05
10.15
10.25
10.35
10.45
7
7.05
7.15
7.25
7.35
7.45
3.5
3.55
3.65
3.75
3.85
3.95
1.8
1.82
1.84
1.90
1.94
1.98
You are expected to optimize the capacitor settings stored in User 1 and
User 2 memories during installation.
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Procedure 6-3 Program the memory
Action
Step 1
Result
Tune the amplifier to the desired frequency
in the User 1 or User 2 position and the
correct antenna port to be saved. Remember
that you cannot store in the default position.
Example: Tune to 14.025 MHz in User 1
segment 1.
Step 2
Press the SAVE button (to the left of the
User 1/2 buttons).
Step 3
If you use more than one antenna for a band,
repeat to store the additional antenna
information.
6
The LED flashes once to
indicate that the
information has been
stored.
Example: You have one antenna on port 4
(beam) and another on port 3 (vertical) and
both are resonant at 14 MHz. Store the beam
settings in User 1 antenna port 4 and the
vertical settings in User 2 antenna port 3.
Step 4
Page 6–10
Move off the band and ensure that the
amplifier returns to the previous location by
pressing any other band button and rekeying
the amplifier on the just-programmed
frequency. If necessary, save the value
again.
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6
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7 Operating the Amplifier from a PC Interface
7.1 Set Up to Operate from a PC 7–2
7.2 Operate from the PC 7–2
The Alpha Remote (AR) AR9500 PC application allows you to access all
functions and features of the ALPHA 9500 from your PC. From this
application you can view and use:
• A simulated front panel with all the buttons replicated, so that you can
click them just as if you were pushing the corresponding button on the
front panel
• Windows that show:
• The amplifier’s normal operational RF parameters
• All power supply voltages used in the amplifier
• The amplifier ID and serial numbers for all resident firmware
• The last 20 faults that the amplifier registered.
• The band edges used by the amplifier
• The segment center frequencies
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7.1 Set Up to Operate from a PC
Procedure 7-1 Set up to operate from a PC
• You can also establish communications with the amplifier via any
NOTE
communications program such as hyperterminal. The
communications parameters are:
— 115,200 baud
— No stop bits
— 8 data bits
— 1 parity bit
— No flow control
• The ALPHA 9500 has both a 9-pin serial port and a USB port on
the back. Only one of these can be active at a time.
7
Step 1
Locate the amplifier’s USB driver (filename CDM-setup.exe) from the
ALPHA website or the CD supplied with the amplifier.
Step 2
Determine which PC COM port is assigned to the ALPHA 9500.
The amplifier is normally assigned to COM port 4 or 5. Confirm this by
checking the computer properties and going to the PC’s Device Manager
to locate the COM ports.
Step 3
Download the AR9500 PC application from the ALPHA website and
install it.
Step 4
When you first run the application, set up the correct COM port for the
application.
Step 5
When the application opens a window that shows graphically all of the
buttons and indicators that are on the front panel, verify that the
application is communicating with the amplifier by mousing over the
ON1 button and left-clicking on it.
If the amplifier does not turn on, verify that the COM port is set to the
correct number.
7.2 Operate from the PC
When the application opens, the main window and the front panel
windows are displayed.
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Operating the Amplifier from a PC Interface
Main window
7
From the main window you can:
• View a list of available COM ports from the drop-down menu labeled
COM Port. Scroll through the list until the port connected to your
amplifier is highlighted.
• View the text editor box at the bottom of the window, which shows
messages about the data being received from the amplifier.
• View the drop-down windows at the top. Below the menus is a list
box for COM port setup.
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Simulated front panel
7
From the simulated front panel you can click any button just as you would
press the button from the amplifier itself.
Tools menu
From the Tools menu you can obtain various types of information.
Clicking this selection sends a telemetry request to the amplifier asking
for that type of data. When the data is received, a window automatically
opens to show what the amplifier sent back. Each time this option is
selected, the information in the window is updated. You can get:
• Radio frequency (RF) data
• Power supply (PS) data
• ID and firmware data
• Fault log of the last 20 fault conditions
• Band edges
• Segment center frequencies
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Operating the Amplifier from a PC Interface
Whether or not any of this data is displayed is controlled by options
selected in the Options menu.
Options menu
From the Options menu, if you Select Windows, the following menu
appears.
7
From this window you can select which parameters to display.
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8 Maintaining and Upgrading the Amplifier
8.1
8.2
8.3
8.4
IMPORTANT
Clean the Chassis 8–1
Retune the Amplifier 8–2
Replace the Tube and Fuses 8–3
Upgrade Firmware 8–4
• The ALPHA 9500 is extremely easy to set up, operate, and
!
maintain. However, failure to carry out each procedure exactly as
described in this manual is likely to lead to amplifier damage,
which is not covered under warranty. Damage to other station
equipment may also result.
• Do not apply oil or grease to any amplifier components. There are
no user-accessible lubrication points in the amplifier.
8.1 Clean the Chassis
Procedure 8-1 Clean the amplifier
Step 1
Power down the amplifier.
Step 2
Disconnect the AC line cord from the power source and lift the cover.
!
WARNING
WARNING! Disconnect the AC line cord from the power source
before lifting the cover for any reason.
Step 3
Clean the interior, particularly high-voltage areas, with a vacuum cleaner
and a soft bristle brush frequently enough to prevent visible accumulation
of dust.
Step 4
Clean the exterior with a mild household liquid detergent. Do not use
chemical solvents, as these may severely damage the front panel or
cabinet finish. Never use an abrasive cleaner.
Step 5
In extremely dusty conditions, secure a thin air filter of the type used for
window air conditioners across the air intake on the rear panel.
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Step 6
Alpha Radio Products
Product Release 1
Replace the cover and reconnect the AC line cord to the power source.
8.2 Retune the Amplifier
Normally you need retune the amplifier only if you change radios,
antennas, or some other aspect of your shack.
When the amplifier is first keyed (that is, moved into State 5) and RF is
sensed, it measures the signal frequency, moves to the appropriate band
and segment, and sets the tune and load-capacitor positions to the values
that you saved for that frequency. If you saved a different antenna position
for that band, it selects the new position.
Your objective in tuning the amplifier (and the drive applied to it) is to
obtain optimum efficiency and linearity at the desired output power. You
must adjust the amplifier for optimum efficiency and linearity at each
specific power level. If you attempt to operate at higher or lower power
levels than those for which you have adjusted, the following happens:
• At higher power, the amplifier flattops, splatters, and (usually)
produces excessive amplifier grid current.
8
• At lower power, the amplifier decreases efficiency considerably.
The ALPHA 2100 in-line dummy load simplifies this adjustment process
by enabling you to switch between dummy load and antenna at the flip of
a switch.
At the factory, the amplifier is tested and tuned into an ALPHA 2100, 50ohm dummy load and the correct tune and load capacitor values are stored
into the default memory-segment positions. You must retune the
amplifier for your particular station setup and save those settings to the
user memories. After the amplifier has switched to the correct tune and
load settings for that particular frequency, you may touch up the capacitor
settings to achieve maximum output.
Procedure 8-2 Retune the amplifier
Step 1
Tune the amplifier for your station setup.
Output tuning on the amplifier is set to broadband and to change
frequencies by up to 100 kHz. They should not normally require retuning.
One-pass auto-tuning is engaged when you press the MEMORY/AUTO
button and the output power is above 150 W. The autotune algorithm
varies the capacitor tune and load settings while paying attention to grid
and plate current to achieve maximum efficiency. The amplifier operates
most efficiently at 1500 W of output power, although it can easily operate
at lower levels.
Step 2
Page 8–2
Save the settings to user memories.
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Alpha 9500 HF Linear Amplifier Operating Manual
Maintaining and Upgrading the Amplifier
When you first install the amplifier, you must save the tune and load
settings for your setup and antennas to the User 1 memory. Note that, for
each band, there are five segment values, representing five different
frequencies across that band. The tune and load settings that are saved in
each location provide a good starting place for the autotune algorithm to
begin. You may choose any favorite frequencies to use as the saved value
for each segment as long as they increase monotonically from segment 1
to segment 5. For a list of frequencies for each segment and band in the
factory default memories, see Table 6-2, page 6–9.
To save settings for each segment and band setting in the User 1 and User
2 memories:
2a Engage autotuning by pressing the MEMORY/AUTO button.
2b Choose the correct antenna on the amplifier.
2c Set a steady carrier and apply drive.
2d With the MEMORY/AUTO button still pressed, increase the drive
until the amplifier achieves 1500 W output.
2e Choose User 1 and the appropriate segment button, and press the
SAVE button. The light flashes once to indicate that the values have
been saved to memory.
2f Repeat across all bands and segments.
8.3 Replace the Tube and Fuses
Step 1
Power down the amplifier.
Step 2
Disconnect the AC line cord from the power source and lift the cover.
!
WARNING
WARNING! Disconnect the AC line cord from the power source
before lifting the cover for any reason.
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88
IMPORTANT
!
Alpha Radio Products
Product Release 1
The amplifier is equipped with a cover interlock switch that removes
primary power from the amplifier, and a crowbar that short-circuits
high voltage to the chassis when the cover is lifted. These interlocks
protect against electric shock resulting from accidental contact with
the lethal voltages inside the amplifier.
Do not disable the interlock switches for any reason.
Procedure 8-3 Replace the tube and fuses
Step 3
Replace the tube.
The amplifier uses a single CPI Eimac Corporation 8877 (3CX1500A7)
ceramic triode tube.
Step 4
Replace fuses.
USE ONLY 20-A, 250-V-RATED FUSES for 190–220 VAC service.
You may use 25-A fuses with caution for line voltages of 90–130 V.
8
Never replace a fuse with one of a different type or greater current rating.
Blowing of one or both primary line fuses indicates that the maximum
safe average power capability of the amplifier has been substantially
exceeded or that an equipment failure has occurred.
The slow-blow fuse F3, located below the primary line fuses, may prevent
damage to the step-start resistors and HV rectifiers in the event of
abnormal turn-on conditions or HV faults. If the AC interlock is defeated
and primary power is applied while the HV crowbar is closed, the stepstart fuses normally blow.
IMPORTANT
!
Step 5
Damage resulting from use of a fuse of incorrect size or type is not
covered under and may void the warranty.
Replace the cover and reconnect the AC line cord to the power source.
8.4 Upgrade Firmware
Occasionally, new firmware for the ALPHA 9500 control board becomes
available for download from the Alpha website.
Go to the Alpha website, retrieve the firmware, and store it on your PC.
Then choose one of the following procedures and follow it to install
firmware.
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Alpha 9500 HF Linear Amplifier Operating Manual
Maintaining and Upgrading the Amplifier
On the Primary Board
Procedure 8-4 Upgrade firmware on the primary board
Step 1
With the amplifier plugged into the power supply, turn the amplifier off.
Step 2
Connect a USB cable (Figure 8-1) between the amplifier and the PC.
Figure 8-1 USB cable
If the PC cannot see an additional COM port when the cable is plugged
into the amplifier, run the VCP installer software.
Step 3
On the PC, install the USB driver, if not already done.
The USB driver allocates the amplifier USB connection to a virtual COM
port (VCP), which looks and behaves like any other COM port.
Step 4
IMPORTANT
On the PC, run the Colt Bootloader and choose the correct COM port and
baud rate.
It is important that you set up the bootloader parameters correctly.
!
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NOTE:
The bootloader menus for setting the COM port and the baud rate
are a little quirky. Although it may look as if there are no other
options from which to choose, there is a little area on the dropdown menu where you can click to show the other choices. If you
have trouble with this, contact ALPHA directly.
The bootloader recognizes only COM ports 1 to 9. The amplifier
is normally assigned to COM port 6. Confirm this by going to the
PC’s Device Manager and checking the computer properties.
The correct baud rate is 115,200.
IMPORTANT
!
Step 5
8
Check only Reload before Program and Reset after Program.
DO NOT check Program data EEPROM, as doing so wipes out all of
your factory calibrations.
With the amplifier still turned off, reset the master microprocessor
(hereafter called the processor) by doing the following in quick
succession:
5a On the PC, press F4.
5b On the amplifier, press the FLT button (just below the 7-segment
display on the far right).
The firmware begins to download to the mains controller; a blue progress
bar shows the progress. The process completes in a few minutes.
Step 6
After the download has completed, repeat Step 5 to reset the processor
again.
Resetting the processor twice ensures that the new firmware loads
correctly and takes effect.
Step 7
On the Secondary
Boards
If the PC cannot see an additional COM port when the USB cable is
plugged into the amplifier, run the VCP installer software.
There are four secondary boards:
• Display board
• Mains board
• Sound generator board
• Stepper motor board
These boards are shown in the figures below.
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Alpha 9500 HF Linear Amplifier Operating Manual
Maintaining and Upgrading the Amplifier
Upgrading the firmware on these boards requires a few more simple steps.
The biggest difference with these upgrades is that you must remove the
cover and front panel to access these boards. In addition, you must install
a special cable between the USB/serial board underneath the powersupply stack and the processor that is being upgraded. You also need a
processor reset cable. You keep your computer connected to the amplifier
via the USB connector on the back of the amplifier and use the same COM
port as before.
Figure 8-2 Display board
8
Figure 8-3 Mains board
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Figure 8-4 Sound generator board
Figure 8-5 Stepper motor board
8
Procedure 8-5 Upgrade firmware on the secondary boards
IMPORTANT
!
Page 8–8
Before you start, review all steps. If you are unsure of any step, call
Alpha Radio Products.
Step 1
Ensure that the amplifier is connected to the PC via the USB cable.
Step 2
Power down the amplifier.
Step 3
Disconnect the AC line cord from the power source and lift the cover.
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Maintaining and Upgrading the Amplifier
!
WARNING
WARNING! Disconnect the AC line cord from the power source
before lifting the cover for any reason.
Step 4
Remove the transformer and front panel assembly.
Place a towel or a soft cloth in front of the amplifier so as not to scratch
the panel.
Step 5
Connect: the programming cable’s end 1 (Figure 8-6) to the USB/serial
board (Figure 8-7).
Figure 8-6 Programming cable, end 1
8
Figure 8-7 USB board
Step 6
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Connect the programming cable’s end 2 (Figure 8-8) to the 3-pin header
adjacent to the board to be upgraded (Figure 8-9).
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Figure 8-8 Programming cable, end 2
Figure 8-9 3-pin header
8
Step 7
Connect the reset-push-button cable to the 5-pin connector.
Step 8
Plug the amplifier in but DO NOT turn it on.
Step 9
Start the Colt Bootloader and select the COM port that was used for the
main-controller upgrade, with the same communications parameters:
• 115,200 baud
• No parity
• 1 stop bit
• 8 data bits
• Flow control = NONE
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Maintaining and Upgrading the Amplifier
Step 10
On the bootloader, choose the correct filename for the board to be
upgraded.
Board
Filename1
Display
Display_Controller_FP_Vx_xx.HEX
Mains
High_Voltage_Mains_Board_Vx_xx.HEX
Sound generator
Sound_Generator_FP_Vx_xx.HEX
Stepper motor
Stepper_Motor_FP_Vx_xx.HEX
1. x_xx is the current version number.
IMPORTANT
!
It is critical that you load the correct firmware for each board. Check
often to ensure that you do not put (for example) code for the main
controller onto the mains board.
Step 11
Press F4 to start the load.
Step 12
Press the reset switch on the cable and note the blue progress bar on the
bootloader.
Step 13
When the load is complete:
13a Unplug the amplifier from the wall.
13b Remove the programming cable and reset switch.
13c Replace the front panel, being careful not to crush any wires between
the front panel and the stepper motors.
Step 14
Remove the other end of the programming cable from the USB/serial
board and replace the original connector.
Step 15
Replace the transformer.
Step 16
Replace the cover and reconnect the AC line cord to the power source.
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9 Diagnosing Faults
9.1 Overview 9–1
9.2 Fault Codes and Resolutions 9–1
9.1 Overview
One of four situations typically results in a fault:
Table 9-1 Fault situations
Fault description
Incorrect gain (output too low or too
high for the input power supplied)
Fault
type
Soft
The OPR switch turns
OFF and the STBY
switch turns ON.
Hard
The amplifier shuts
OFF completely.
High reflected power (SWR)
Incorrect plate voltage (too high)
Amplifier action
RF arc in output circuit including
antenna
In fault mode, the tube is biased off and the relays are placed in bypass
mode, so that RF from the amplifier goes directly to the antenna. The FLT
(Fault) switch below the 7-segment display lights and the fault number is
displayed.
If the tube current exceeds about 1.6 A (causing the amplifier to switch to
ON1), diagnose and resolve the fault as described below.
9.2 Fault Codes and Resolutions
Fault numbers and descriptions are as follows:
Table 9-2 Fault code summary
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Number
Description
1
Gain fault
2
Tap not found
3
Soft Ip trip
4
Hard Ip trip
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Table 9-2 Fault code summary
Number
Description
5
Vp under voltage
6
Output relay closure fail
7
Output relay may be stuck
8
Bandswitch set failure
9
Tune cap zero failure
10
Load cap zero failure
11
Over-temperature
12
Reflected power too high
13
Clear over-temperature
14
Plate voltage too high
15
Grid current too high
16
Autotune failure
17
Plate current too high with amplifier unkeyed
18
Input power too high
Fault code 1
Description
Gain fault.
Explanation
The power gain (power output divided by power input) of the amplifier
has fallen below a value of 10 (10 dB). The normal gain of the amplifier
when properly tuned is around 30 (15 dB), so this represents a substantial
drop in gain. It is, in fact, the first line of protection for the unit, since
almost any major problem in the amplifier (or even in the load connected
to the amplifier) manifests as a drop in gain.
The amplifier attempts to automatically clear this fault after 4 seconds
and, if the key line is still asserted, go into OPERATE mode. If the fault
reoccurs, this process repeats indefinitely. If it occurs often in a short
period of time, it is important that you determine the underlying cause and
correct the problem.
If you operate the amplifier remotely, the control software should be
capable of taking the necessary steps over the USB or RS232 interface to
“safe” the amplifier. Although no maximum number of attempts to get
back online are specified, it is possible, if this fault occurs repeatedly, that
consequential damage to the amplifier may result. Such damage may not
be covered under warranty.
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Alpha 9500 HF Linear Amplifier Operating Manual
Diagnosing Faults
As noted previously, this fault (and several others) are inhibited (disabled)
if the drive power into the amplifier from the exciter is less than 20 W.
The amplifier is generally safe at this drive power level, and it provides a
window for you to exercise the various controls to either get the amplifier
tuned to within the nominal gain range or determine the underlying cause
of the problem.
Resolution
1. . Ensure that the load is good under low power. Put the amplifier in
bypass mode, and note the standing wave ratio (swr) reported by the
exciter. If it is very high, check the antenna/load.
2. If you have recently switched to a new exciter, ensure that it is not
putting out excessive power. It has been found that even new
transceivers from reputable suppliers develop problems that cause
them to put out power much higher than expected, either transiently
or continuously. High input power can cause the amplifier to saturate,
and the reported gain to drop. Drive powers above 100 W can damage
the amplifier and cause this fault. Within-range drive powers at the
wrong frequency can also cause this fault.
3. Ensure that the plate voltage (Vp on the digital meter) is within limits
(3.0 to 3.8 kV).
• At the low end of this range, the amplifier struggles to meet the
gain specification. It is possible that the mains board has set an
inappropriate tap on the primary of the transformer. This can
happen for several reasons, but a procedure has been
implemented that enables you to override the automatic tap
selection feature and force the amplifier to set any desired
primary taps. For information on how to force tap selection,
contact ALPHA technical support.
• At the high end of this range, it is also possible that an incorrect
tap has been set, although this normally causes a different fault
code.
Fault code 2
Description
Tap not found.
Explanation
The mains board has measured a line voltage that does not correspond to
an acceptable primary tap setting.
The mains board has a set of relays that can select an appropriate
combination of primary windings for the power transformer. The tap can
be selected either automatically based on the mains board estimate of line
voltage, or by force when you tell the amplifier which tap to use.
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To ease initial installation of the amplifier, it is shipped with automatic tap
selection enabled. This is appropriate for most situations, but it is possible
that a particular situation may fake the voltage estimation circuitry out,
and cause the amplifier to select an inappropriate tap. This can result in
off-nominal conditions for the plate and heater voltages.
The reasons for this fault are several. It is likely that either the AC supply
is floating (has a poorly defined ground reference) or the waveform is
significantly distorted (by spikes or other irregularities).
It is possible to operate the amplifier with some of these less-than-perfect
power sources by enabling the force-tap-selection option. For information
on how to force tap selection, contact ALPHA technical support.
Resolution
1. Measure the line voltage using an accurate voltmeter. Compare this
value with the reported value in the amplifier telemetry stream. This
is most easily done by running the AlphaRemote/9500 software. The
line voltage is reported in the rectangle around the meter selection
buttons. If necessary, this can be done with the amplifier plugged in
but in the OFF condition.
2. If the reported and measured values differ by more than a few volts,
investigate the cause. Possible reasons are:
• Poor AC voltage waveform (check with an oscilloscope)
• Poor ground (check from chassis to Line A and Line B)
If neither of these cases seem to exist, it is possible that the
measurement circuitry on the mains board has drifted. If this is the
case, contact ALPHA technical support.
3. Assuming the value is being reported correctly, compare this value to
the values in the following table. There are 5 possible primary tap
selections, with values as indicated.
Tap number
Min voltage
Max voltage
1
89.9
109.9
2
110.0
135.0
3
189.9
209.9
4
210.0
229.9
5
230.0
265.0
The amplifier selects the tap appropriate to the range reported as
being measured. If the measured value does not fall into one of the 5
ranges, the amplifier does not turn on unless you activate manual tap
selection.
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Alpha 9500 HF Linear Amplifier Operating Manual
Diagnosing Faults
Fault code 3
Description
Soft Ip trip.
Explanation
The current in the high voltage (HV) circuit is greater than 1.6 A.
Normal plate current for the amplifier at 1.5 kW output power is in the
range 0.8 to 1.1 A. Above this value, the tube may be at or above its rated
plate dissipation. This trip is set so that, if the plate current exceeds 1.6 A
for a short time, it trips and goes into bypass mode. You should
investigate the cause and resolve the problem to avoid damage to the
amplifier.
Resolution
• Ensure that the drive power to the amplifier is not too high. This could
be because of a problem at the exciter. Put the amplifier in bypass
mode and transmit with the exciter. The power should normally be 65
W or less, normally more like 50 W. It is even possible that the exciter
has a problem that is causing it to put out brief high power spikes. It
is possible that the exciter and amplifier are interacting to produce
this effect.
Fault code 4
Description
Hard Ip trip.
Explanation
The amplifier has tripped completely off, and you have turned it on again
to either of the ON positions. The HV circuit current exceeds about 2.5 A.
The mains board contains a latching relay and associated circuitry that
trips when the current reaches that level.
Under most circumstances, the mains board reports a fault 3 (soft Ip)
when the plate current exceeds 1.6 A. If this software fault does not
happen, a hardware circuit kicks in and essentially unplugs the amplifier.
This is normally caused by a direct arc from the HV circuit to ground,
inside the tube or elsewhere.
Resolution
• Reduce the drive power or retune the amplifier.
Fault code 5
Description
Vp under voltage.
Explanation
The mains board monitors the plate voltage (HV, Vp) for approximately
2 seconds after the amplifier is turned fully on (ON 2).
If Vp fails to reach approximately 2.8 kV during this time, the mains
board reports this fault code.
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Resolution
Alpha Radio Products
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1. Ensure that the mains board is selecting the correct primary
transformer tap. See fault code 2 for information on how to do this.
2. If the correct primary tap is being selected, then the problem is
elsewhere. Unplug the amplifier, remove the top cover, and inspect
the mains board and high voltage board. Unplug each of the
transformer connectors and inspect them for problems.
Fault code 6
Description
Output relay closure fail.
Explanation
The master controller monitors the state of the output relay using an
auxiliary DC bias applied through a pair of RF chokes. This allows it to
determine that the output relay has traveled to the closed condition, and
that it is safe to bias the tube to OPERATE mode.
Resolution
• Call Alpha Radio Products at 303-473-9232.
Fault code 7
9
Description
Output relay may be stuck.
Explanation
If the output relay appears to be closed when the amplifier is keyed up, it
is possible that the output relay is stuck in the ÖN condition for one of
several reasons. See Fault code 6 for more information.
Resolution
• None. You should not see this fault in the field.
Fault code 8
Description
Bandswitch set failure.
Explanation
The stepper motor controller processor is unable to land the apparent
bandswitch position on the correct setting within the precision required.
Resolution
1. Turn the amplifier off and back on.
2. If the fault does not clear, turn the amplifier off, unplug it from the
AC mains., plug it back in, and power it up again.
3. If the fault still does not clear, with the amplifier on, press a
bandswitch on the front of the amplifier.
Fault code 9
Page 9–6
Description
Tune cap zero failure.
Explanation
The stepper motor controller is unable to determine the zero position for
the tune capacitor.
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Alpha 9500 HF Linear Amplifier Operating Manual
Diagnosing Faults
The tune capacitor has an opto-interrupter that is actuated by a small vane
on the drive shaft. When the amplifier is turned to the ON2 or ON/AMP
position, the stepper controller attempts to move the vane until it just
occludes the opto-interrupter. This position is registered as a 0 (zero) for
the tune capacitor, and represents the minimum attainable capacitance for
that capacitor. Maximum capacitance is attained when the stepper motor
controlling the tune capacitor has taken 100 steps. The stepper motor
controller counts how many steps it takes, adding when the capacitance
increases and subtracting when the capacitor decreases. The count
(between 0 and 100) is the tune capacitor position. When the master
controller (MC) sends a command indicating that a new tune capacitor
position is desired, the stepper motor controller knows in which direction
and for how many steps to turn the capacitor.
Resolution
1. Unplug the amplifier, wait 30 seconds, and plug it back ON to the
ON2 or ON/AMP setting.
2. Even if the last fault is still fault 9, attempt to turn the tune capacitor
from the buttons on the front panel or from the AR9500 PC
application. If the capacitor responds, the fault may have cleared.
3. If the fault persists, contact ALPHA technical support. If possible,
send them the contents of the fault log. To display the fault log, from
the AR9500 PC application, open the Fault window and select Tools
> Get fault log.
Fault code 10
Description
Load cap zero failure.
Explanation
The stepper motor controller is unable to determine the zero position for
the load capacitor.
The load capacitor has an opto-interrrupter that is actuated by a small vane
on the drive shaft. When the amplifier is turned to the ON2 or ON/AMP
position, the stepper controller attempts to move the vane until it just
occludes the opto-interrupter. This position is registered as a 0 (zero) for
the load capacitor, and represents the minimum attainable capacitance for
that capacitor. Maximum capacitance is attained when the stepper motor
controlling the load capacitor has taken 100 steps. The stepper motor
controller counts how many steps it takes, adding when the capacitance
increases and subtracting when the capacitor decreases. The count
(between 0 and 100) is the load capacitor position. When the master
controller (MC) sends a command indicating that a new load capacitor
position is desired, the stepper motor controller knows in which direction
and for how many steps to turn the capacitor.
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Resolution
Alpha Radio Products
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1. Unplug the amplifier, wait 30 seconds, and plug it back ON to the
ON2 or ON/AMP setting.
2. Even if the last fault is still fault 10, attempt to turn the load capacitor
from the buttons on the front panel or from the AR9500 PC
application. If the capacitor responds, the fault may have cleared.
3. If the fault persists, contact ALPHA technical support. If possible,
send them the contents of the fault log. To display the fault log, from
the AR9500 PC application, open the Fault window and select Tools
> Get fault log.
Fault code 11
Description
Over-temperature.
Explanation
The amplifier has a built-in temperature sensor to ensure that the tube
does not overheat. The sensor is located on the cathode board, in the tube
deck compartment. Air from the blower motor impinges on this board and
then flows up through the tube anode fins. Normally the temperature it
reports is at approximately this air temperature. Since the air has already
been drawn over other parts of the amplifier, it is some 10–20C warmer
than ambient air. The trip value is currently set to 50C.
The amplifier goes to ON AMP, but in bypass mode and with the tube
biased off. This should reduce plate dissipation to a minimum and, if the
air system is working correctly, the temperature should start to fall. When
it reaches a safe value, the amplifier can be put in service again, as
indicated by fault code 13 (clear temperature).
9
Resolution
1. Ensure that there is air exiting the amplifier from the hexagonal
pattern of holes near the rear left. If not, this is likely the cause.
2. If there is no air leaving the amplifier when it is in the ON AMP
position, assuming that all other front panel displays appear normal,
ensure that there is nothing obstructing the air flow at the inlet (on the
right rear of the amplifier) or at the exit.
3. Ensure that the external fan is operating. The fan is at the right rear of
the amplifier, covered by a wire grill. It should start to rotate in the
ON AMP condition. Use a flashlight if necessary to avoid the
appearance of nonrotation due to the stroboscopic effect. This can be
done without removing the amplifier cover.
4. Check the internal airways of the amplifier. Unplug the amplifier,
remove the cover, and ensure that the blower motor (to the right of the
tube) is clean and that its impeller rotates when moved gently with a
long screwdriver. Look down into the tube and ensure that the
passages between the anode fins are not blocked, for example by an
accumulation of dust.
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Alpha 9500 HF Linear Amplifier Operating Manual
Diagnosing Faults
5. Ensure that amplifier is being operated with a tuning condition that
does not result in poor efficiency.
6. Ensure that the tube standing bias (keyed, with no RF) is not greater
than 500 mA. Key the amplifier with the meter set to Ip to make this
measurement. If Ip is greater than 500 mA, then there may be a
problem in the cathode bias circuitry, on the cathode board, or in the
tube itself.
Fault code 12
Description
Reflected power too high.
Explanation
The amplifier monitors the apparent reflected power at its output. If the
power is above the set value, currently 375 W, the amplifier goes into
BYPASS mode and attempts to clear the fault.
Resolution
• Ensure that antennas and other equipment installed after the amplifier
were installed correctly.
Fault code 13
Description
Clear over-temperature.
Explanation
The amplifier has recovered from fault 11 (temperature fault).
Resolution
9
• See fault 11.
Fault code 14
Description
Plate voltage too high.
Explanation
The plate voltage has exceeded a safe value, currently 3800 Vdc.
Resolution
1. Ensure that the AC mains voltage is correct.
2. Unplug the amplifier, plug it back in, wait for at least 30 seconds, then
turn it back on.
Fault code 15
Description
Grid current too high.
Explanation
The amplifier monitors the grid current and, if it exceeds a safe value for
a period of time, it goes into BYPASS mode and reports this fault. The
usual cause is too much drive for the current output loading condition. It
may represent amplifier overdrive (excessive input power) or incorrect
tune and load capacitor settings.
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Diagnosing Faults
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Resolution
Alpha Radio Products
Product Release 1
• Reduce the drive or retune.
Fault code 16
Description
Autotune failure.
Explanation
The autotune algorithm has encountered a problem that causes it to go
through a large number of iterations without being able to find an
acceptable tune condition, and has been stopped.
Resolution
• Reduce the drive and restart the auto-tune.
Description
Plate current too high with amplifier unkeyed.
Explanation
When the amplifier is unkeyed, the plate current should be quite low.
Some failure conditions can cause the plate current to exceed a safe level
and produce this fault code.
Fault code 17
9
Resolution
1. If the tube is shorted out, replace it.
2. Ensure that the HV circuit is functioning properly.
Fault code 18
Description
Input power too high.
Explanation
The input drive power from the exciter is greater than a preset threshold,
currently 100 W.
Resolution
Page 9–10
• Reduce the input power to within proper limits.
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Terminology
Terminology
NOTE: For detailed explanations of the following terms, see various publications including the latest
American Radio Relay League (ARRL) Handbook.
A
AC — Alternating current. Electric current whose
magnitude and direction vary with time.
ALC — Automatic Level Control. Technology
that automatically controls output power.
ampere — Unit of electric current.
ARRL — American Radio Relay League. US
national organization of amateur radio
operators. For more information, go to
www.arrl.org.
AWG — American wire gauge. Standard method
of denoting wire diameter.
B
B1 — Modulation class AB1. Amplifier-circuit
class that provides good linearity in push-pull
configuration.
C
CW — Continuous wave. Electromagnetic wave
of constant amplitude and frequency.
D
dB — Decibel. Logarithmic unit of measure of the
power of sound relative to a reference level.
E
exciter — Radio that provides RF drive for the
ALPHA 9500 to operate.
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Terminology–1
Alpha 9500 HF Linear Amplifier Operating Manual
Terminology
Alpha Radio Products
Product Release 1
F
FCC — Federal Communications Commission.
For more information, go to www.fcc.gov.
FM — Frequency modulation. Modulation scheme
in which information is conveyed over a carrier
wave by variations in frequency.
FSK — Frequency-shift keying. Type of
frequency modulation in which information is
conveyed by shifts in the output frequency
between predetermined values.
H
HF — High frequency. Radio frequency within the
range 3–30 MHz.
HV — High voltage. Electrical circuit in which the
voltage used presents risk of both electric shock
and electrical arcing.
Hz — Hertz. One periodic event per second.
I
Ip — Idling plate current. Plate current measured
when the amplifier is keyed and RF is not
present.
K
key — Signal from the radio to the amplifier that
instructs the amplifier to switch from receive to
transmit mode because the radio is ready to
generate RF power. The (programmable) delay
between keydown and RF out is generally 8–12
ms. When the amplifier is keyed, it is in State 5.
kV — Kilovolt. 1000 V.
kVA — Kilovolt-ampere. 1000-W capability.
kVA * 0.8 = kilowatts.
kW — Kilowatt. 1000 W.
L
LED — Light-emitting diode. Semiconductor
diode that emits incoherent narrow-spectrum
light, providing a form of electroluminescence.
Terminology–2
LV — Low voltage. Electrical circuit in which the
voltage used presents risk of electric shock but
only minor risk of electrical arcing.
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Alpha 9500 HF Linear Amplifier Operating Manual
Terminology
M
mA — Milliampere. 10-6 A.
MHz — Megahertz. 106 Hz.
O
OPR — Operate.
PCB — Printed circuit board. Board that
mechanically supports and electrically connects
electronic components.
P
PSK — Phase-shift keying. Digital modulation
scheme in which information is conveyed by
changes, or modulations, in the phase of a
reference signal.
Q
QSK — Quadrature-shift keying. Digital
modulation scheme in which the transmitter is
on only for the duration of each dot or dash and
switches to receive between each dot or dash,
allowing the operator to hear any signal being
sent.
R
RCA — Radio Corporation of America. Also a
type of interconnecting plug.
RF — Radio frequency. Frequency within the
range 3 Hz–300 GHz.
RG-x/x — Coaxial cable type.
RMS — Root mean square. Statistical measure of
the magnitude of a varying quantity such as a
wave.
RTTY — Radioteletype. Telecommunications
system consisting of two or more teleprinters
using radio as the transmission medium.
S
SSB — Single-sideband. Modulation scheme that
refines upon amplitude modulation.
SSTV — Slow-scan television. Picturetransmission method for transmitting and
receiving static pictures via radio.
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STBY — Standby. Mode in which an electronic
appliance is turned off but under power and
ready to activate on command.
SWR — Standing-wave ratio. Ratio of the
amplitude of a partial standing wave at an
antinode (maximum) to the amplitude at an
Terminology–3
Alpha 9500 HF Linear Amplifier Operating Manual
Terminology
Alpha Radio Products
Product Release 1
adjacent node (minimum). Measure of antenna
and feedline efficiency.
T
T/R — Transmit /receive.
transceiver — Device that has both a transmitter
and a receiver within the same circuitry or
chassis.
U
UHF — Ultra-high frequency. Radio frequency
US — United States.
within the range 300–3000 MHz (3 GHz).
V
VAC — Volts of alternating current.
VDC — Volts of direct current.
Terminology–4
VSWR — Voltage standing-wave ratio. Example:
If VSWR = 1.2:1, the maximum standing-wave
amplitude is 1.2 times greater than the
minimum standing-wave amplitude.
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